Conventionally, the image forming apparatus in which an electrostatic latent image formed on a rotating photosensitive drum is developed into a toner image by using a liquid developer containing a toner and a carrier liquid, and the toner image developed from the electrostatic latent image is primary-transferred onto an intermediary transfer member and further, the toner image transferred on the intermediary transfer member is secondary-transferred onto a recording material has been known. In this apparatus, development of the electrostatic latent image into the toner image has been carried out while the liquid developer accommodated in a developer container is supplied to a drum surface by the developing roller contacted to the drum surface.
Further, in the above-described apparatus, in order to remove the liquid developer containing transfer residual toner remaining on the photosensitive drum after the primary transfer, a cleaning blade (hereinafter simply referred to as a blade) formed in a plate shape with a rubber or the like. However, when this blade is kept in contact with the photosensitive drum on which rotation of this blade is stopped, the blade can adhere to the drum surface with vaporization of the liquid developer remaining on the drum surface or a stripe-shaped deposition matter can be formed at the contact position of the drum surface. In order to avoid this, the blade is provided so as to contactable to and separable from the photosensitive drum and is controlled so as to be separated (spaced) from the drum surface at the time of an end of an image forming job and so as to be contacted to the drum surface at the time of a start of an image forming job. Then, in the case where the blade is separated from the drum surface, a liquid accumulation of the liquid developer formed at the contact position is moved with rotation of the photosensitive drum, and has been collected in the developer container by the developing roller.
Incidentally, in the case of an apparatus capable of forming a color image, a liquid accumulation containing toners of a plurality of colors is formed on the drum surface by the blade in some instances. In such a case, when the liquid accumulation containing the toners of the plurality of colors is collected in the developer container, colors of liquid developers are mixed with each other in the developer container and cause color mixture. When this color mixture of the liquid developers occurs, a color hue to an image changes. Therefore, an apparatus in which a liquid accumulation is removed from a drum surface by supplying a carrier liquid to a blade has been proposed (Tokuhyo 2008-508562).
Further, as an image forming apparatus capable of forming a color image, although an image forming apparatus uses a dry developer, not the liquid developer, an image forming apparatus of a tandem type in which a plurality of photosensitive drums are juxtaposed in a movement direction of an intermediary transfer belt has been conventionally proposed (Japanese Laid-Open Patent Application (JP-A) 2010-66452).
Recently, also in the image forming apparatus using the liquid developer, in order to realize further downsizing, there is a demand for constituting the image forming apparatus of a tandem type as described in JP-A 2010-66452. However, in that case, the color mixture of the liquid developer due to the above-described liquid accumulation is more liable to occur. For example, onto a magenta drum surface provided on a downstream side of an intermediary transfer belt (hereinafter simply referred also to as a belt) with respect to a movement direction of the belt, toner which is a part of a yellow toner image transferred onto the belt on a side upstream of the magenta drum with respect to the movement direction of the belt is moved in some instances (hereinafter, this is referred to as re-transfer, for convenience). Therefore, on the magenta drum surface, a liquid accumulation containing toners of yellow and magenta is capable of being formed.
Further, in order that the liquid accumulation containing the toners of magenta and yellow is not collected in the developer container with separation of the belt, as in the apparatus described in Tokuhyo 2008-508562 described above, it would be considered that the carrier liquid is supplied. However, when a mechanism for supplying the carrier liquid is provided for each of the plurality of photosensitive drums, a structure becomes complicated and a large space for installation is needed, so that it was difficult to employ the mechanism for supplying the carrier liquid. Therefore, an image forming apparatus in which a simple constitution is employed and in which the liquid accumulation formed on the drum surface is not collected by the blade has been conventionally desired, but such an image forming apparatus has not yet been proposed.